Delivery Apparatus and Methods for Vertebrostenting

ABSTRACT

The invention relates to a method of delivering and deploying a stent into a curvilinear cavity within a vertebral body or other bony or body structure. The invention also relates to devices that may be used to perform the steps to deliver and deploy a stent.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Docket No.SOT-004, entitled “Devices and Methods for Vertebrostenting,” and filedof even date herewith, the disclosure of which is being incorporatedherein by reference in its entirety. This application claims priority toand the benefit of U.S. provisional patent application Ser. No.60/875,114 filed Dec. 15, 2006, and U.S. provisional patent applicationSer. No. 60/875,173 filed Dec. 15, 2006, the disclosures of which arebeing incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates generally to the field of orthopedicdevices to treat fractured bone in the spine, and more particularly toan orthopedic instrument and implant system that can be used tofacilitate bone cement treatment of a vertebral compression fracture.

BACKGROUND OF THE INVENTION

There are many disease states that cause bone defects in the spinalcolumn. For instance, osteoporosis and other metabolic bone conditionsweaken the bone structure and predispose the bone to fracture. If nottreated, certain fractures and bone defects of the vertebral body mayproduce intolerable pain, and may lead to the development of deformityand severe medical complications.

Bone weakening may also result from benign or malignant lesions of thespinal column. Tumors often compromise the structural integrity of thebone and thus require surgical stabilization and repair of defects withbiocompatible materials such as bone grafts or cements. Bone tumors ofthe spine are relatively common, and many cause vertebral compressionfracture.

More than 700,000 osteoporotic compression fractures of the vertebraeoccur each year in the United States—primarily in the elderly femalepopulation. Until recently, treatment of such fractures was limited toconservative, non-operative therapies such as bed rest, bracing, andmedications.

One surgical technique for treating vertebral compression fracture caninclude injecting or filling the fracture bone or bone defect withbiocompatible bone cement. A relatively new procedure known as“vertebroplasty” was developed in the mid 1980's to address theinadequacy of conservative treatment for vertebral body fracture. Thisprocedure involves injecting radio-opaque bone cement directly into afracture void, through a minimally invasive cannula or needle, underfluoroscopic control. The cement is pressurized by a syringe or similarplunger mechanism, thus causing the cement to fill the void andpenetrate the interstices of a broken trabecular bone. Once cured, thecement stabilizes the fracture and eliminates or reduces pain. Bonecements are generally formulations of non-resorbable biocompatiblepolymers such as PMMA (polymethylmethacrylate), or resorbable calciumphosphate cements which allow for the gradual replacement of the cementwith living bone. Both types of bone cements have been used successfullyin the treatment of bone defects secondary to compression fractures ofthe vertebral body.

One clinical issue associated with vertebroplasty is containment of thecement within the margins of the defect. For instance, an osteoporoticcompression fracture usually compromises portions of the cortical bonecreating pathways to cement leakage. Thus, there is a risk of cementflowing beyond the confines of the bone into the body cavity. Cementleakage into the spinal canal, for instance, can have grave consequencesto the patient.

Yet another significant risk associated with vertebroplasty is theinjection of cement directly into the venous system, since the veinswithin the vertebral body are larger than the tip of the needle used toinject the cement. A combination of injection pressure and inherentvascular pressure may cause unintended uptake of cement into thepulmonary vessel system, with potentially disastrous consequencesincluding embolism to the lungs.

One technique which has gained popularity in recent years is a modifiedvertebroplasty technique in which a “balloon tamp” is inserted into thevertebral body via a cannula approach to expand or distract thefractured bone and create a void within the cancellous structure.Balloon tamps are inflated using pressurized fluid such as salinesolution. The inflation of a balloon membrane produces a radial force onthe bone and forms a cavity in the bone. When deflated and removed, themembrane leaves a cavity that is subsequently filled with bone cement.The formation of a cavity within the bone allows for the injection ofmore viscous cement material which may be relatively less prone toleakage.

In certain instances, such as the treatment of acute or mobilefractures, the balloon is also effective at “reducing” the fracture andrestoring anatomic shape to a fractured body. In particular, balloondilatation in bone is maximally effective if the balloon device istargeted inferior to, or below, the fracture plane. In this instance,the balloon dilatation may distract, or lift, a fracture bone fragment,such as the vertebral body endplate.

In other instances, such as chronic or partially healed fractures,balloons are less effective at “reducing” the fracture because radialforces are insufficient. Often the bone in an incompletely healingfracture is too dense and strong, and requires more aggressive cuttingtreatment, such as a drill or reamer tool to create a sufficient cavity.In these more challenging cases, the ability to inject bone cement intoa cavity created by a balloon or a reamer in the vicinity of thefracture is typically sufficient to stabilize the bone and relieve pain,even in the absence of fracture reduction.

One limitation to the use of such methods has been the difficulty intargeting the location at which the cavity should be created. Knowntechniques require access to the vertebral body using straight cuttingand reaming tools which are only able to access a limited region of thevertebral body being treated, generally only within one side of thevertebral body. A cavity created using these techniques can only treatone side of a vertebral body being targeted, resulting in an unevendistribution of bone cement that cannot completely stabilize thevertebral body. As a result, multiple entry points on different sides ofthe vertebral body are generally required in order to provide asymmetrical distribution of bone cement around a central axis of thevertebral body. These multiple entry points significantly increase thetime necessary for the procedure, the portion of the body being treated,and the amount of bone cement being injected, and as such cansignificantly increase the risks associated with treatment of a patient.

SUMMARY OF THE INVENTION

The present invention is directed towards novel methods and devices forpreparing a cavity in bone, deploying a cement-directing stent device,and injecting bone cement into the device. The methods and devicesdisclosed herein can allow a cavity to be created in a vertebral bodyalong a curvilinear pathway, allowing for a substantially symmetricaldistribution of bone cement over a central vertical axis of a vertebralbody. This can allow a vertebral body to be successfully and completelystabilized from a single surgical access point and using a single stentdevice.

One aspect of the invention can include a method of deploying a stentwithin an enlarged curvilinear void created in a bony structure. Themethod can include the steps of: inserting a distal end of a stentdelivery system through a cannula and into a curvilinear void created ina bony structure, deploying a self-expanding cement-directing stentwithin the curvilinear void, wherein the self-expanding stent isreleasably attached to the distal end of the stent delivery system,attaching a cement injecting syringe to the proximal end of the stentdelivery system, injecting cement through the stent delivery system andinto the stent, terminating the cement injection when the volume ofcement injected exceeds the interior volume of the expanded stent, andreleasing the stent from the stent delivery system.

In one embodiment, the stent delivery system can include at least one ofa proximal deployment mechanism, an internal flexible guidewire, and aninternal flexible tube, such as a polymer extrusion. The self-expandingcement-directing stent can include a multifilament braided, polymerimpregnated, self-expanding, cement-directing stent collapsed on thedistal end of the guidewire and restrained in a collapsed condition by atubular polymer sheath. The self-expanding cement-directing stent can bedeployed by slideably uncovering the tubular sheath to release andexpand the stent within an enlarged curvilinear void. The self-expandingcement-directing stent can be alternatively or further deployed byremoving the internal flexible guidewire and/or the polymer extrusion.

Alternatively, another method of stent deployment eliminates the needfor the tubular sheath. The self-expanding cement-directing stent ismaintained in a collapsed state solely by the internal flexibleguidewire and/or the polymer extrusion. Once positioned in the enlargedcurvilinear void, deployment of the self-expanding cement-directingstent can be accomplished solely by removing the internal flexibleguidewire and/or the polymer extrusion.

In one embodiment, the self-expanding cement-directing stent can beconnectably attached to the proximal deployment mechanism by a hollowtube assembly. The stent can be released by actuating the proximaldeployment mechanism.

One aspect of the invention can include a method of deploying a stentwithin an enlarged curvilinear void created in a bony structure. Themethod can include the step of inserting a stent catheter assembly intoan enlarged curvilinear void through a cannula and into the curvilinearvoid created in a bony structure, wherein the stent catheter assemblycan include a proximal deployment mechanism, an internal flexibleguidewire, a multifilament braided, polymer impregnated, self-expanding,cement-directing stent collapsed on the distal end of the guidewire andrestrained in a collapsed condition by a tubular polymer sheath, andconnectably attached to the distal end of the deployment mechanism by ahollow tube assembly.

The method can further include the steps of deploying the self-expandingcement directing stent by slideably uncovering the tubular sheath torelease and expand the stent within the enlarged void within the bonystructure, removing the internal flexible guidewire, attaching a cementfilled cement injecting syringe to the proximal deployment mechanism,injecting cement into the proximal deployment mechanism through thehollow tube assembly into the stent, pressurizing the cement to causethe complete filling of the stent interior, terminating the filling whenthe volume of cement injected exceeds the interior volume of theexpanded stent, and releasing the stent from the hollow tube assembly.

In one embodiment, the self-expanding cement-directing stent can includea multifilament braided, polymer impregnated, self-expanding,cement-directing stent. In one embodiment, the stent delivery system caninclude a handle and an elongate shaft. The stent can be releasablyattached to a distal end of the elongate shaft. In one embodiment, thestent is further releasably attached at a distal end thereof, The stentcan be released by actuating a user control mechanism on the handle. Theelongate shaft can include at least one of an inner shaft, an outershaft, a tubular sheath, a flexible guidewire, and an internal polymerextrusion.

In one embodiment, prior to the deploying step the self-expandingcement-directing stent is collapsed on a distal end of at least one ofthe inner shaft, the guidewire, and the polymer extrusion. Theself-expanding cement-directing stent can be deployed by retracting atleast one of the inner or outer shaft, the flexible guidewire, and thepolymer extrusion.

In one embodiment, prior to the deploying step the self-expandingcement-directing stent can be restrained in a collapsed condition by thetubular sheath. The self-expanding cement-directing stent can bedeployed by slideably retracting the tubular sheath to allow the stentto self-expand within the enlarged curvilinear void. In one embodiment,the deploying step includes actuating a rotating cam mechanism.

The invention is also drawn to stent delivery systems and componentsthereof adapted for use with any of the methods described above.

Another aspect of the invention can include a stent delivery system fordeploying a stent within an enlarged curvilinear void created in a bonystructure. The stent delivery system can include a handle and anelongate shaft adapted to releasably hold a self-expandingcement-directing stent at a distal end thereof. The elongate shaft caninclude a sheath and at least one of an inner and an outer shaft. Thestent delivery system can also include at least one user controlmechanism adapted to deploy the stent.

In one embodiment, the at least one user control mechanism includes arotating cam mechanism. Actuating the rotating cam mechanism can retractthe sheath towards the handle. In one embodiment, actuating the rotatingcam mechanism simultaneously extends the distal end of at least one ofthe inner and the outer shaft away from the handle.

In one embodiment, a distal end of the handle can include an interfaceelement adapted to releasably engage at least a portion of proximal endof a cannula. The stent delivery system can also include a stent releasemechanism adapted to release the stent from the elongate shaft.

Another aspect of the invention can include a user control mechanism fora stent delivery device. The user control mechanism can include asupport element, at least one cam shaft helically positioned on thesupport element, a linear support sleeve, and at least one pin engagingthe cam shaft and the linear support sleeve. The cam shaft and thelinear support sleeve force the pin linearly along an axial extent ofthe user control mechanism upon a rotation of the support element.

In one embodiment, the at least one pin is attached to an elongate shaftextending from a distal end of the user control element. The elongateshaft can include at least one of an inner shaft, an outer shaft, and asheath.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different views. Also, the drawings are notnecessarily to scale, emphasis instead generally being placed uponillustrating the principles of the invention. In the followingdescription, various embodiments of the present invention are describedwith reference to the following drawings, in which:

FIG. 1A is a schematic side view of a stent including a plurality ofholes, in accordance with one embodiment of the invention;

FIG. 1B is another schematic side view of the stent of FIG. 1A;

FIG. 1C is a schematic rear perspective view of the stent of FIG. 1A,showing the plurality of holes;

FIG. 1D is a schematic front perspective view of the stent of FIG. 1A,showing the plurality of holes;

FIG. 1E is another schematic rear perspective view of the stent of FIG.1A;

FIG. 1F is another schematic front perspective view of the stent of FIG.1A;

FIG. 2A is a schematic plan view of a delivery system for a stent, inaccordance with one embodiment of the invention;

FIG. 2B is another schematic plan view of the delivery system of FIG.2A;

FIG. 2C is a photograph of a delivery system inserted in a patient, inaccordance with one embodiment of the invention;

FIG. 2D is a schematic side view of a cement filled stent inserted in avertebral body, in accordance with one embodiment of the invention;

FIG. 3A is a schematic plan view of a delivery system and collapsedstent, in accordance with one embodiment of the invention;

FIG. 3B is a schematic perspective view of the handle of the deliverysystem of FIG. 3A;

FIG. 3C is a schematic plan view of the handle of the delivery system ofFIG. 3A;

FIG. 3D is a schematic perspective view of the handle of the deliverysystem of FIG. 3A, with the flexible guidewire (e.g., nitinol wire)retracted;

FIG. 3E is a schematic perspective view of the handle of the deliverysystem of FIG. 3A, with the sheath retracted;

FIG. 3F is a schematic perspective view of the handle of the deliverysystem of FIG. 3A, with the flexible guidewire (e.g., nitinol wire) andsheath retracted;

FIG. 3G is a schematic perspective view of a stent coupled to thedelivery system of FIG. 3A, with the sheath retracted;

FIG. 3H is a schematic perspective view of the handle of the deliverysystem of FIG. 3A, with the sliding mechanism extended forward;

FIG. 3I is a schematic perspective view of the handle of the deliverysystem of FIG. 3A, with the sliding mechanism retracted to anintermediate position;

FIG. 3J is a schematic perspective view of an expanded stent coupled tothe delivery system of FIG. 3A;

FIG. 3K is a schematic perspective view of the handle of the deliverysystem of FIG. 3A, with the inner core assembly (i.e., polymer extrusionand flexible guidewire) removed;

FIG. 3L is a schematic perspective view of the handle of the deliverysystem of FIG. 3A, with a syringe attached;

FIG. 3M is a schematic perspective view of the handle of the deliverysystem of FIG. 3A, with the cement piston inserted to push throughadditional cement;

FIG. 3N is a schematic perspective view of the handle of the deliverysystem of FIG. 3A, with the cement piston removed;

FIG. 3O is a schematic perspective view of the handle of the deliverysystem of FIG. 3A, with the locking mechanism unlocked;

FIG. 3P is a schematic perspective view of the rear of the handle of thedelivery system of FIG. 3A, with the locking mechanism unlocked;

FIG. 4A is a schematic side view of a handle for a delivery system witha rotational cam mechanism, in accordance with one embodiment of theinvention;

FIG. 4B is a schematic side view of the handle of FIG. 4A after beingturned;

FIG. 4C is a schematic end view of another handle for a delivery systemwith a rotational cam mechanism, in accordance with one embodiment ofthe invention;

FIG. 4D is a schematic side view of the handle of FIG. 4C;

FIG. 4E is a schematic plan view of the handle of FIG. 4C;

FIG. 4F is another schematic end view of the handle of FIG. 4C;

FIG. 4G is a schematic perspective view of a linear sleeve for thehandle of FIG. 4C;

FIG. 4H is a schematic perspective view of a support element on a linearsleeve for the handle of FIG. 4C;

FIG. 4I is a schematic perspective view of the handle of FIG. 4C;

FIG. 4J is another schematic perspective view of the handle of FIG. 4C;

FIG. 5 is a schematic side view of a handle for a delivery system with arotational threaded mechanism, in accordance with one embodiment of theinvention;

FIG. 6 is a schematic side view of a handle for a delivery system with ageared mechanism, in accordance with one embodiment of the invention;

FIG. 7 is a schematic side view of a handle for a delivery system with asliding belt mechanism, in accordance with one embodiment of theinvention;

FIG. 8A is a schematic perspective view of a handle for a deliverysystem with a triggering mechanism, in accordance with one embodiment ofthe invention;

FIG. 8B is a schematic perspective view of the interior cam mechanism ofthe handle of FIG. 8A;

FIG. 9 is a schematic perspective view of a delivery system inserted ina cannula, in accordance with one embodiment of the invention;

FIG. 10A is a schematic end view of a handle for another deliverysystem, in accordance with one embodiment of the invention;

FIG. 10B is a schematic side view of the handle of FIG. 10A;

FIG. 10C is a schematic plan view of the handle of FIG. 10A;

FIG. 11A is a schematic perspective view of the handle of FIG. 10A;

FIG. 11B is a schematic perspective view of the handle of FIG. 11A afterrotation of a rotating user control mechanism;

FIG. 11C is a schematic perspective view of the handle of FIG. 11B afterremoval of the top cap;

FIG. 11D is a schematic perspective view of the handle of FIG. 11C afterdepression of sliding of the stent release buttons;

FIG. 12A is a schematic sectional side view side view of a releasableattachment mechanism attached at a distal end of a collapsed stent, inaccordance with one embodiment of the invention;

FIG. 12B is a schematic sectional side view of the releasable attachmentmechanism of FIG. 12A after expansion of the stent;

FIG. 12C is a schematic sectional side view of the releasable attachmentmechanism of FIG. 12A after detachment from the distal end of the stent;and

FIG. 12D is a schematic sectional side view of the releasable attachmentmechanism of FIG. 12A injecting filler material into the stent afterremoval of the inner rod.

DETAILED DESCRIPTION OF THE INVENTION

The present invention discloses methods and apparatus for introducing astent into a curvilinear or other shaped cavity created within thecancellous bone of a fractured vertebral body or other bony structure.The invention also discloses methods and apparatus for injecting cementinto the stent and into the surrounding cancellous bone throughpositioned exit holes in the stent.

The methods and apparatus disclosed herein allow for a covered stent tobe safely inserted into the vertebral body through the same entryprofile as current vertebral compression fracture treatments. Once inplace, the delivery apparatus can direct cement into the stent andthrough the designated holes into the vertebral body. This can allow forthe controlled flow of cement away from the spinal canal and towards theanterior side of the vertebral body. Unlike cardiovascular stentdelivery systems, the delivery systems disclosed herein have a positiveattachment to the stent for cement injection and stent placementadjustability, thus increasing the stability, controllability, andsafety of the system during surgical procedures.

In one embodiment of the invention, expansion of a stent in response toretraction of an outer sheath covering the stent, and maintaining it ina collapsed configuration, is performed in an orthopedic rather thancardiovascular environment. In one embodiment, the delivery system mayhave certain features that exhibit some similarity to cardiovascular andendoscopic medical device designs, but may also have several mechanicaladditions specially designed and configured for orthopediccompatibility.

In one embodiment, the delivery system is configured to compensate forstent foreshortening in a closed cavity environment. Foreshortening of astent occurs when a stent is expanded from a radially collapsedconfiguration to a radially expanded configuration, with the expansionresulting in a reduction in length as the diameter of the stent isincreased. This length reduction results in the expanded stent beingretracted back from the distal wall of the cavity in which it isdeployed, which in turn results in the expanded stent failing tocompletely fill the cavity in which it is deployed. The delivery systemsdisclosed herein therefore differ from the usual stent delivery systemsthat are used in vascular or duct environments where longitudinal spaceis available to allow foreshortening.

In one embodiment, the stent can be attached to the distal tip of thedelivery system and is not automatically released from the device duringstent expansion. As a result, physicians are able to pull the stent outof the vertebral body during the surgical procedure, compress, recoverwith the outer sheath and redeliver the stent if the physician is notsatisfied with the original placement. This recovery and redeploymentcan greatly increase the chances of correctly placing the stent in themost advantageous, and safe, position within a patient.

In one embodiment of the invention, the delivery system has the abilityto retract an outer sheath maintaining the stent in a collapsedconfiguration from a side portal in order to minimize the length of thedelivery system. Cement injection back pressures significantly increasewith longer cement injection channels. By incorporating a slit into theouter sheath to allow the outer sheath extrusion to pass over the shaftsof the delivery system and be pulled sideways or linearly through thehandle, the overall delivery system length can be reduced. This allowsthe cement to travel a shorter distance to fill the stent, and thereforereduces the injection pressure required to inject cement into the stentat substantially zero pressure. This reduction in injection pressure canincrease the usability of the delivery system, while reducing thepotential for failure of the injection process, and increasing thesafety of the system.

In one embodiment, the method of cement injection through the deliverysystems disclosed herein may provide a safer and more efficient means oftreating a vertebral compression fracture than current vertebralcompression fracture treatments. In one embodiment, cement may beinitially injected by a syringe through the inner shaft of the deliverysystem. The delivery system can direct the cement straight into thestent and through the designated outlet holes in the stent into thesurrounding cancellous bone. Once injection with a syringe becomesdifficult, for example as a result of the cement curing, a solid pistoncan be inserted into the inner shaft to deliver more cement. The innerlumen of the delivery system can, in one embodiment, hold approximately1.5 cc of cement from the proximal to the distal end. The cement pistoncan also be used to completely clear the inner shaft of cement toprevent cement back flow out of the pedical. With the delivery systemand stent attachment at the distal tip of the delivery system, cementinjection becomes more controlled than in more traditional techniques ofvertebroplasty and kyphoplasty.

Stent

In one embodiment of the invention, a stent can include a multifilamentco-braided shaped structure and a self-expanding structure compositewhich is collapsible to an elongated tubular shape suitable to fitwithin a tubular sheath assembled to a novel delivery catheter. Theouter wall of the stent can be impregnated in preferred regions with apolymer to form a thicker, relatively less permeable wall. The polymerimpregnated co-braided wall is further perforated with holes or slots inpreferred locations. An example cement directing stent for use with thisinvention is disclosed in U.S. Patent Publication No. 2005/0261781 A1 toSennett et al., the disclosure of which is incorporated herein byreference in its entirety. The stent geometry is optimized to fit withina reamed or balloon-expanded cavity located approximately within theanterior ⅔ of a vertebral body. The cavity is formed by a sequentialmethod using a number of specifically designed instruments. An examplestent 100 is shown in FIGS. 1A-1F.

In one embodiment of the invention, the stent 100 can be sized tosubstantially conform to the dimensions of a predetermined cavitycreated within a vertebral body. The stent 100 can be configured to becollapsible, thus allowing delivery of the stent 100 through arelatively small diameter access cannula. The stent 100 can also have aself-restoring shape, allowing the stent to automatically expand to itsoriginal shape, corresponding substantially with the dimensions of thecavity into which it is inserted, without the need for inflation of thestent 100 by the injection of filler material or other fluids orsubstances. In one embodiment, the stent 100 may be self-restoring to anexpanded configuration, at least because it is constructed, at least inpart, from a shape-memory material, such as, but not limited to,nitinol. The stent 100 may be constructed, at least in part, as abraided structure 110.

In one embodiment, expansion of the stent 100 does not generate adistraction force on the end plates of the vertebral body and does notcompact the interior cancellous bone structure of the vertebral body.Upon expansion of the stent 100 within the vertebral body, fillermaterial (such as bone cement) can be injected into the stent 100 to atleast partially fill the interior of the stent 100. In one embodiment,the injection of filler material does not substantially alter the shapeand dimensions of the stent 100, other than to conform the stent, ifnecessary, to the shape of the cavity in which it is disposed.

In one embodiment of the invention, the wall of the stent may include atleast one hole 120 or permeable region allowing filler material to leavethe interior of the stent 100 and enter the vertebral body. The at leastone hole 120 or porous region can allow for the controlled and directeddistribution of filler material within the vertebral body. The wall ofthe stent 100 may include a plurality of holes of various sizes and/or aplurality of regions of differing permeability, allowing for a greateror lesser escape of filler material in different directions. The wall ofthe stent 100 may also include at least one baffle or othernon-permeable region preventing the escape of filler material in certaindirections. In general, the total cross-sectional area of the holesexceeds that of a cement inlet hole 140, to prevent excess back pressureor buildup of pressure in the interior of the stent.

In one embodiment, the stent 100 may have a proximal region 130 that isconfigured to be releasably mounted to a delivery system and includesthe inlet hole 140 to allow for the injection of cement. The stent 100can also have a closed distal region 150 to be positioned away from thedelivery system and to be placed against the distal end of the cavity inwhich it is placed.

In one embodiment, the method of treating the patient may involveexternal reduction by extension, i.e. physical manipulation of thepatient when placing the patient on the operating table before treatmentof the vertebral fracture site. The method of treating the patient canalso involve stabilizing the vertebral body, not distracting the upperand lower end plates using the stent as an expansion device.

Delivery System

An example of a delivery system can be seen in FIG. 2A. The deliverysystem 200 can include a handle portion 205 at a proximal end, and ahollow elongate shaft 210 extending towards a distal end. A stent 215can be releasably held at the distal end of the hollow elongate shaft210.

In one embodiment of the invention, the delivery system 200 can beconfigured to releasably couple to a cannula that is insertedpercutaneously from the posterior approach through the outer tissue of apatient and anchored into the bone of the vertebral body to a suitabledepth. The hollow elongate shaft 210 can be configured to slidablyextend through the cannula such that the stent 215 protrudes from thedistal end of the cannula and into a curvilinear cavity formed withinthe vertebral body. The stent may be configured to extend at a specificangle, or along a predetermined arc, to conform to the axis of thecavity. In an alternative embodiment, the stent may extend straight outfrom the distal end of the hollow elongate shaft 210.

The flexibility and resiliency of the stent is well adapted for use incavities having a variety of shapes, including curvilinear, cylindrical,tapered, conical, etc. The stent may be flexible, such that it may bedeflected by the walls of the cavity and therefore conform substantiallyto the curvature or shape of the cavity when inserted. In a furtheralternative embodiment, the cavity may extend straight out from thedistal end of the cannula, and no curvature or deflection of the stentis required for correct insertion of the stent into the cavity.

In one embodiment, a flange 220 and key 225 may be fitted to the handleportion 205 of the delivery system 200 at the proximal end of the hollowelongate shaft 210. The flange 220 may enable the delivery system to bereleasably locked to the cannula to ensure stability of the deliverysystem 200 during the procedure. The key 225 may be configured to matewith a slot in the cannula to ensure that the delivery system 200 isinserted into the cannula in the correct circumferential orientation. Inan alternative embodiment, the delivery system 200 may include a lockingmechanism, latch, or other appropriate means of releasable engagementwith the cannula. In a further alternative embodiment, no means oflocking the delivery system 200 to the cannula may be required.

In one embodiment, a sheath 230 may be used to releasably maintain thestent 215 in a collapsed configuration during insertion through thecannula and into the cavity. The collapsed configuration may besubstantially the same diameter as the diameter of the hollow elongateshaft 210 (i.e. a diameter configured to fit slidably through thecannula). The sheath 230 may be a hollow elongate flexible tube ofplastic, fabric, wire mesh, composite, metal or other appropriatematerial, that can slideably extend over the hollow elongate shaft 210and stent 215 to hold the stent 215 at a set diameter substantiallyequal to the diameter of the hollow elongate shaft 210.

The proximal end 235 of the sheath 230 may extend through an exit hole240 in the handle 205 of the delivery system 200. An elongate slot maybe inserted in a portion of the proximal end 235 of the sheath 230 toallow the sheath 230 to be pulled out through the exit hole 240 withouttearing. In one embodiment, a handle may be placed on the end of thesheath 230 to assist in pulling the sheath 230 out through the exit hole240.

In use, the sheath 230 is slid over the hollow elongate shaft 210 andstent 215 to hold the stent 215 in a collapsed configuration. Once thestent 215 has been inserted through the cannula and into the cavity, thesheath 230 can be pulled back through the exit hole 240 in the handle205. This retracts the sheath 230 back along the hollow elongate shaft210 and off the stent 215. The stent 215 is then free to self-expand toits original shape, which may, in one embodiment, conform substantiallywith the shape of the curvilinear cavity. In one embodiment, a marking245 may be placed on the sheath 230 near the proximal end 235 toindicate to a user when the sheath 230 has been retracted far enough touncover the stent 215.

In addition to the sheath 230, or possibly in place of the sheath 230, apolymer extrusion and/or a flexible guidewire 250 may be insertedthrough the handle 205 and hollow elongate shaft 210 to provide aninternal force to extend the distal end of the stent 215 and assist inholding the stent 215 in a collapsed, or partially collapsed,configuration. The polymer extrusion may be an elongated hollow polymershaft made of any flexible polymer such as PEBAX, Nylon PET or PTFE. Theflexible guidewire 250 may be an elongate solid or hollow rod ofstainless steel, aluminum, plastic, or another appropriate material,that may slideably extend through the hollow elongate shaft 210 of thedelivery system 200, with the distal end of the flexible guidewire 250abutting against the interior distal end of the stent 215 to force thestent forward.

In one embodiment, the flexible guidewire 250 may also include aguidewire handle 255 that can assist the user in pulling and pushing onthe guidewire 250 as required. A mounting element 260 may be releasablyconnected to the end of the handle 205 with a bayonet retention featureor other attachment feature and through which the flexible guidewire 250passes. The mounting element 260 may also be connected to the polymerextrusion that extends down to the stent 215 and is disposed coaxiallybetween the flexible guidewire 250 and the hollow elongate shaft 210 ofthe delivery system 200. This extrusion may be used, for example, toprovide a smooth, low friction boundary between the guidewire 250 andthe hollow elongate shaft 210. The polymer extrusion may be of a lengthsuch that the extrusion also assists in maintaining the stent 215 in acollapsed configuration prior to insertion and deployment in the cavity.The mounting element 260 may be used to cover a luer lock, or othermounting feature, that may be used to releasably hold a syringe once theinner core assembly (i.e., polymer extrusion and guidewire 250) has beenremoved.

The inner core assembly (i.e., polymer extrusion and guidewire 250) mayprovide multiple functions for the delivery system 200. For example, theinner core assembly (i.e., polymer extrusion and guidewire 250) may beused to assist in maintaining the stent 215 in a collapsed configurationprior to insertion and deployment in the cavity. The inner core assembly(i.e., polymer extrusion and guidewire 250) may also be used tocounteract any foreshortening of the stent 215 that may occur duringexpansion.

In one embodiment, a sliding mechanism 265 can also be used tocounteract foreshortening of the stent 215 as a result of expansionwithin the cavity. The sliding mechanism may be fixedly coupled to thehollow elongate shaft 210 of the delivery system 200, and be slidablycoupled to the handle 205 of the delivery system 200. By sliding thesliding element 265 forward, the entire hollow elongate shaft 210 andattached stent 215 can be pushed forward, thus pushing the distal end ofthe expanded stent 215 towards the distal end of the cavity. After thestent 215 has been pushed to the end of the cavity, the sliding element265 can be slid backwards by a small amount to counteract anyforeshortening of the proximal end of the stent 215 that may result fromthe pushing process. A releasable locking mechanism 270, including aspring mounted locking element 275, can be used to ensure that thesliding element 265 is locked in place when not needed. In oneembodiment, markings may be placed on the handle 205 to indicate thelength of travel of the sliding element 265.

Once a stent 215 has expanded and been correctly positioned within acavity, the stent 215 may be filled with cement, cement analogue, orother filler material, by fitting a syringe to the luer lock, or otherlocking mechanism at the proximal end of the hollow elongate shaft 210,after the inner core assembly (i.e., polymer extrusion and guidewire250) has been removed. The cement can then flow through the hollowelongate shaft 210 and into the interior of the stent 215, after whichit can flow into the vertebral body through the carefully positionedholes in the stent 215.

Once the stent has been filled, the stent can be released from thedelivery system 200 and the system removed from the patient. A lockingmechanism 280 may be included in the handle 205 of the delivery system200 to releasably hold the stent 215 to the hollow elongate shaft 210.The locking mechanism 280 may be attached to an elongate element that isattached at its distal end to the proximate end of the stent 215. Thelocking mechanism 280 may also include a slider 285, or a switch, clasp,or other user interface element, to unlock the stent 215 from theelongate element and/or hollow elongate shaft 210 once the stent hasbeen correctly positioned and filled. In one embodiment, a pin 290 maybe removably inserted into the locking mechanism 280 to ensure that thestent 215 is not released accidentally.

It should be noted that at all steps of a method using theabove-identified delivery system 200, medical imaging techniques, suchas fluoroscopy, may be used to image the interior of the vertebral bodyand confirm the location and status of the stent 215, cement, andcavity.

An example a delivery system 200 with the sheath 230 retracted and thestent 215 expended is shown in FIG. 2B. An example of this deliverysystem 200 inserted into a patient can be seen in FIG. 2C. Across-section of a cement filled stent 215 inserted into a vertebralbody 292 is shown in FIG. 2D. In this figure, large arrows 294 indicatethe direction of the cement leaving through holes 296 in the stent 215in order to stabilize a fracture 298. Small arrows correspond to areasof lower permeability of the stent 215, through which nominal amounts ofcement leave the stent 215 to further anchor the stent 215 and fill anyremaining voids in the cavity.

Method of Use

An embodiment of the invention can include a method of using thedelivery systems described herein to insert and deploy a stent deviceinto a cavity created in a vertebral body. The cavity may be acurvilinear cavity. In an alternative embodiment, the cavity may be ofany appropriate size and shape, with a stent selected to be configuredto substantially conform to the size and shape of the cavity created.

In one embodiment of the invention, a procedure for using the devicesdisclosed herein can be used to produce a curvilinear cavity within avertebral body, and place a stent within the cavity created within thevertebral body. The stent can be a self-expanding, covered stent thatallows interdigitation and prevents leakage of bone cement in undesireddirections. In one embodiment, a single stent can be placed at amid-line location of a vertebral body, rather than placing multiplestents on either side of the mid-line, thus reducing the time andfluoroscopy exposure require during a surgical implantation procedure.

In one embodiment, the method of creating a cavity for within avertebral body, or other bony body, can include first creating aposterior pathway to the vertebral body, using a extrapedicular orintrapedicular approach, with a Jamshidi needle and/or K-wire. This maybe performed, for example, using a dual C-arm technique to place andmedialize the Jamshidi needle/K-wire to the fullest extent.

A working channel and trocar assembly can then be inserted along thepathway created by the Jamshidi needle/K-wire. This can be performed,for example, by locking the trocar into the working channel, insertingthe working channel into the pathway, and tapping the assembly intoplace until the distal tip of the trocar and working channel extends, inone embodiment, 1-3 mm beyond the posterior wall of the vertebral body.The trocar can then be removed, leaving the open working channel inplace.

A curved pathway through the vertebral body can then be created using acurved drill. This may be achieved using any of the drill arrangementsdescribed herein. In one embodiment, the drill depth markings at theuser interface are set to “0”mm prior to insertion into the workingchannel. The drill can then be locked into the working channel with thekey facing in the medial direction, thus ensuring the correct directionof curvature of the drill within the vertebral body. The handle of thedrill can then be rotated to advance the drill tip into the vertebralbody, with fluoroscopy, or some other appropriate technique, used todetermine when the desired depth of penetration is achieved. The drillcan then be removed and the depth markings on the user interfacerecorded. In one embodiment, the drill tip is oriented in thecontralateral anterior quadrant of the vertebral body, thus assuringproper cavity positioning and bilateral cement filling.

In one embodiment, a larger cavity can then be created within thevertebral body by reaming out the hole created by the curved drill witha curved reamer. This may be achieved, for example, by first setting thedepth markings on the user interface of the reamer to match thoserecorded for the drill depth, thus assuring that the reamer ispositioned correctly within the vertebral body. The reamer can then beadvanced fully into the pathway created by the drill and locked into theworking channel, with the position of the reamer confirmed usingfluoroscopy or some other appropriate technique. The blade of the reamercan then be opened, for example by rotating a portion of the handle ofthe reamer, and reaming can be carried out by rotating the handle. Inone embodiment, the reamer may be stopped approximately 1-3mm beforeapproaching the distal tip of the working channel, with the positionconfirmed by fluoroscopy, or some other appropriate technique. The bladecan then be closed (for example by rotating a portion of the handle inthe opposite direction), and the reamer removed. In one embodiment, dueto blade deflection, the cavity created by the reamer can have a slighttaper from the distal end to the proximal end.

Once a cavity has been created, a stent delivery system can be lockedinto the working channel to correctly position a stent within thevertebral body. Once the stent has been positioned, a sheath coveringthe stent can be removed to deploy and expand the stent, and cement canbe injected into the stent by attaching a syringe to the proximal end ofthe delivery system. The desired amount of cement can be injected intothe stent with fluoroscopy, or some other appropriate technique, beingused to monitor the flow of cement into the stent. Once the requisiteamount of cement has been injected, the stent can be released from thedelivery system and the delivery system removed from the workingchannel, thus leaving the stent in place within the vertebral body. Theworking channel can then be removed and the access pathway sutured orotherwise closed.

One example embodiment may include inserting a delivery system 200 intothe cannula such that the covered stent is extended beyond the distalend of the cavity and into the curvilinear cavity. An example of adelivery system prior to insertion into a cannula is shown in FIGS.3A-3C. Once the delivery system 200 is fully inserted within thecannula, the delivery system 200 can engage with, and be locked in placeby, a locking element associated with the cannula. In one embodiment ofthe invention, the delivery system 200 may be extended through thecannula until a user can feel resistance to the forward movement,indicating that the end of the collapsed stent is abutting against thedistal end of the cavity created within the vertebral body. In analternative embodiment, the length of the cavity may be carefullymeasured such that the end of the collapsed stent will automaticallyextend to the end of the cavity upon insertion of the delivery system200. In addition to these techniques, or in place of these techniques,representative fluoroscopic photos or movies, or use of otherappropriate medical imaging techniques, may be taken to ensure thecorrect placement of the stent within the cavity.

Once the stent has been correctly positioned within the cavity in itscollapsed configuration, it may be expanded within the cavity. In oneembodiment, the inner core assembly (i.e., polymer extrusion andguidewire 250) inserted through the center of the delivery system 200and abutting against the distal end of the stent may be pulled back, forexample by pulling on a handle 255 attached to the flexible guidewire250 and twisting off the bayonet retention feature of the mountingelement 260 attached to the polymer extrusion, thus relieving the forceon the distal end of the stent that is assisting in maintaining thestent in a collapsed configuration. In one example embodiment, theflexible guidewire 250 and handle 255 may be pulled back byapproximately two inches, or by a greater or lesser distance, asrequired. In an alternative embodiment, the flexible guidewire 250 andhandle 255 may be removed completely. In a further alternativeembodiment, there is no need for the inner core assembly (i.e., polymerextrusion and guidewire 250) to be inserted within the delivery system200, with the sheath 230 alone being sufficient to maintain the stent ina fully collapsed configuration. An example of a flexible guidewire 250and handle 255 being retracted can be seen in FIG. 3D.

Once the force on the distal end of the stent, provided by the flexibleguidewire 250 and/or polymer extrusion, has been removed, the stent isready to be expanded. Expansion of the stent can be executed byretracting the sheath 230, for example by pulling on a handle attachedto the sheath, by a predetermined amount. A mark 245 may be placed onthe sheath 230 to indicate when the sheath 230 has been pulled back bythe correct amount. Retracting the sheath 230 removes the externalrestrictive force on the stent and allows it to self-expend to itspreformed, free-state configuration. This may, in one embodiment of theinvention, substantially conform to the size and shape of the cavity. Anexample of a sheath 230 after being retracted can be seen in FIGS. 3Eand 3F. In an alternative embodiment, the sheath 230 can be removedprior to the polymer extrusion being removed. An example of a stent 215with the sheath 230 retracted but with the polymer extrusion remainingin place and extended to the distal end of the stent 215 can be seen inFIG. 3G.

In one embodiment of the invention, expansion of the stent 215 can alsoresult in a certain amount of foreshortening at the distal end of thestent 215. This foreshortening, which is caused by the increase in thediameter of the stent 215 as it expands resulting in a responsivedecrease in the length of the stent 215, may retract the end of thestent 215 slightly from the distal end of the cavity. This may becompensated for by providing a force to push the entire stent 215forward until the distal end of the expanded stent 215 abuts against thedistal end of the cavity. This may be achieved through the use of asliding mechanism 265 that is configured to allow for the extension andretraction of the entire stent 215 and elongated shaft 210 arrangementalong the axis of the shaft. By releasing the locking mechanism 270 onthis sliding mechanism 265, the stent 215 and elongated shaft 210 can bepushed forward by the required amount. The sliding mechanism 265 canthen re-engage the locking mechanism to lock the stent at a finalposition. An example of the sliding mechanism 265 pushed forward withinthe handle 205 can be seen in FIG. 3H.

In one embodiment, forcing the expanded stent 215 forward may result acertain amount of foreshortening of the stent 215 at its proximal end(i.e. the end attached to the elongated shaft 210 of the delivery system200). Here, after forcing the stent 215 forward using the slidingmechanism 265, the sliding mechanism 265 may be retracted by a smallamount to counteract any foreshortening at the proximal end of the stent215. Again, the sliding mechanism 265 may be locked into position oncethe stent 215 has been correctly positioned. As before, fluoroscopicimages, or other appropriate medical images, may be taken to confirm thepositioning and expansion of the stent at the distal end of the cavity.In one embodiment of the invention, the polymer extrusion may also beused to extend the expanded stent after foreshortening due to theexpansion. An example of the sliding mechanism 265 retracted after beingpushed forward within the handle 205 can be seen in FIG. 3I. An exampleof a fully expanded stent 215 coupled to a hollow elongated shaft 210with a sheath 230 retracted can be seen in FIG. 3J.

As mentioned above, the polymer extrusion can perform the function ofcollapsing the stent by stretching the stent out longitudinally oraxially, by applying a force in that direction from within the stent.The proximal end of the stent is fixed to the elongate shaft 210 and thedistal end of the stent is stretched and held in place by the polymerextrusion which is locked in position to the handle 205 by the mountingelement 260. With the stent collapsed, it can be moved easily down theworking channel, thereby eliminating the need for a sheath in thedelivery system.

After correct positioning of the expanded stent 215, the polymerextrusion can be removed completely from the delivery system 200 byreleasing and retracting the mounting element 260 from the handleportion 205. Removing the polymer extrusion leaves a hollow shaft 210through the center of the delivery system 200 and into the interior ofthe expanded stent 215. This hollow shaft can then be used for theinjection of cement, or other material, into the stent. An example ofthe delivery system with the polymer extrusion removed can be seen inFIG. 3K.

Injection of cement into the stent may be performed by releasablyconnecting the end of a syringe 310 to the hollow shaft at the pointvacated by the polymer extrusion mounting element 260. In one embodimentof the invention, a 10 cc threaded syringe may be used, although inalternative embodiments, any appropriate injection device may beutilized. In one embodiment, the proximal end of the hollow shaft mayinclude a luer lock 320, or other releasable locking arrangement, thatmay engage the end of the syringe 310 and engage it with the hollowshaft 210. An example of a syringe 310 attached to the handle 205 of thedelivery system 200 can be seen in FIG. 3L. Alternatively, instead ofdirectly rigidly connecting the syringe 310 to the handle 205, a rigidor flexible extension tube can be interdisposed between the syringe 310and the handle 205. The extension tube allows the physician to have hishands out of the fluoroscopic field and also provides the opportunity toreorient the syringe 310, e.g., by forming an “elbow” or other angularconnection, so that the syringe 310 is not fixedly cantilevered axiallyfrom the delivery system 200.

Once the syringe 310 is in place, the cement, or other material, such asa cement analogue, can be injected into the hollow shaft 210 of thedelivery system 200 and into the expanded stent 215. Injection of cementmay be continued until the stent 215 is completely filled and cementflows out of the designated holes in the stent into the vertebral body.Once enough cement has flowed out of the stent 215 and into thevertebral body to provide the required level of interdigitation betweenthe stent 215 and vertebral body, the injection can be stopped. Again,fluoroscopic images, or other appropriate medical images, may be takento confirm that the stent has been filled and the required amount ofcement has flowed out into the vertebral body at the correct positions.

In one embodiment of the invention a cement piston 325 may be used topush additional cement in the hollow shaft 210 into the stent 215, forexample when high cement viscosity has resulted in incomplete filling ofthe cavity. This may be achieved by simply detaching the syringe 310,and pushing the cement piston 325 back into the hollow shaft 210 toforce the additional cement in the shaft 210 into the stent 215. Thismay be important if the physician is not satisfied with the amount ofcement filling prior to removal. In one embodiment, the hollow shaft 210can hold 1.5 cc of cement, or other material, with the cement piston 325capable of pushing any percentage of that volume into the stent 215, asrequired. Once the correct amount of cement has been injected into thestent 215, the cement piston 325 can again be removed. An example of thecement piston 325 forcing cement through the shaft 210 can be seen inFIG. 3M. An example of the handle 205 of the delivery system 200, afterthe cement piston 325 has been removed again, can be seen in FIG. 3N.

After the stent 215 has been filled with cement, and the correct amountof cement has exited the stent 215 through the exit holes tointerdigitate with the vertebral body, the stent 215 can be releasedfrom the delivery system 200 and the delivery system 200 removed. In oneembodiment of the invention, a locking mechanism 280 may be used to holdthe stent 215 onto the delivery system 200. This locking mechanism 280may include any appropriate means of releasably engaging the proximalend of the stent, including, but not limited to, a clamping mechanism, agrasping mechanism, sliding mechanism, a pressure fit between an outershaft, the proximal end of the stent, and the inner hollow shaft, or anyother appropriate mechanism. In one embodiment, the locking element 285may include a slide, switch, or other element at the proximal end of thedelivery system, allowing the locking mechanism to disengage from thestent when required. A removable pin 290, or other locking device, maybe inserted into the delivery system 200 to ensure that the deliverysystem 200 is not disengaged from the stent 215 inadvertently, beforethe cement has been fully injected. An example of the locking mechanism280 after the pin 290 has been removed and the locking mechanism 280opened is shown in FIGS. 3O and 3P.

Once the stent has been released from the delivery system, the deliverysystem can be unlocked and removed from the cannula. After this, thecannula may be removed and the surgical incision closed.

In an alternative embodiment, a delivery system including a handleadapted to move multiple components of the delivery system with amovement of a single user control mechanism can be used to deploy astent within a cavity created within a vertebral body. This user controlmechanism can include a mechanism such as, but not limited to, arotating mechanism, a sliding mechanism, a trigger mechanism, or anyother appropriate mechanical, electrical, and/or magnetic mechanism.

Employing a user control mechanism to control a number of functions ofthe delivery system can both simplify and speed up the deploymentprocess, while reducing the number of steps that need to be performed bya user during the deployment process. This can increase the efficiencyof the delivery system while increasing the safety of the deploymentmethods for a patient being treated. In one embodiment, a user controlmechanism can control the retraction of a sheath covering the stent, themovement of an inner shaft, and/or the movement of an outer shaft. Theinner shaft can include, but is not limited to, a flexible guidewire, ahollow flexible shaft, and/or another appropriate elongate elementconfigured to extend through the interior of an outer shaft. The outershaft can include, but is not limited to, a hollow elongate shaftconfigured to releasably engage the stent at its distal end.

In an alternative embodiment, additional and/or different functions ofthe delivery system can be controlled by a single user controlmechanism. These functions can include, but are not limited to,injecting filler material such as cement into the stent, releasing thestent, locking, and/or unlocking, the delivery system to/from thecannula, curving the distal end of the flexible shaft to facilitatedeployment of the stent within a curved cavity, and/or any otherappropriate function of a stent delivery system.

In one embodiment, a user control mechanism is adapted to retract theouter sheath of the elongate shaft of a delivery system to allow thestent to be fully deployed within a cavity in a vertebral body. At thesame time, the inner and outer shafts of the elongate shaft are movedforward to compensate for any foreshortening of the stent duringretraction of the sheath, as described above. This allows the stent tobe deployed in its expanded configuration at the full distal extent ofthe cavity. The user control mechanism can be configured to move thesheath and the inner and outer shafts simultaneously in oppositedirections by set amounts, with the sheath being retracted towards thehandle of the delivery system while the inner and outer shafts areextended outwards away from the handle.

The distance by which each of the sheath and the inner and outer shaftshould be moved relative to each other is dependent upon factors thatcan include the size and shape of the stent and the cavity in which thestent is being deployed. For example, in one embodiment, the sheath canbe retracted by a distance equal to or greater than the length of thestent to ensure that it is fully retracted from the stent in order toallow the stent to expand fully. The inner and outer shafts, incontrast, can be extended by a distance equal to the foreshortening ofthe stent as it expands from its collapsed configuration to its expandedconfiguration. In one embodiment, the inner and outer shafts can beextended out from the handle by the same distance. In an alternativeembodiment, the inner shaft and the outer shaft can be extended out fromthe handle by different distances.

Example user control mechanisms for moving multiple components of adelivery system can be seen in FIGS. 4A-8B.

FIGS. 4A and 4B show a handle 400 for a delivery system with arotational cam mechanism 410 before and after being rotated. Therotational cam mechanism 410 includes three separate slotted cam shaftswrapped helically on a support element 420 surrounding the central shaft425 of the handle 400. An outer grip 430 covers the support element 420and central shaft 425 and engages with the support element 420. Pinsassociated with each of the outer shaft, the inner shaft, and the sheathengage with the slotted cam shafts such that a rotation 435 of thesupport element 420 will force the pins axially along the central shaftof the delivery device in a direction and distance controlled by theangle and direction of each slotted cam shaft.

More specifically, a first slotted cam shaft 440 engages with a firstpin 445 attached to the outer shaft of a delivery system. A secondslotted cam shaft 450 engages with a second pin 455 attached to theinner shaft of the delivery system. And, a third slotted cam shaft 460engages with a third pin 465 attached to a sheath. As a result, as theouter grip 430 is rotated about the central shaft 425 of the handle 400,the first pin 445 and second pin 455 will be forced axially forward 470toward the distal end of the handle 400, resulting in the inner shaftand outer shaft being extended outwards from the distal end of thehandle 400 (and therefore compensating for any foreshortening of thestent during deployment). Simultaneously, the third pin 465 will bepulled axially rearwards 475 toward the proximal end of the handle 400,resulting in the sheath being pulled rearwards 475 towards the handle400 (and therefore exposing the stent).

In one embodiment, the helical paths for each of the inner shaft andouter shaft have the same angle, resulting in the distal ends of theinner shaft and outer shaft each being forced forward 470 the samedistance. In an alternative embodiment, the helix paths for each of theinner shaft and outer shaft may be different, resulting in the distalends of the inner shaft and outer shaft being forced forward 470 by adifferent amount. In a further alternative embodiment, at least one ofthe inner shaft and outer shaft may be stationary.

Additional axially slotted cam shafts can be located at the distal endof the first slotted cam shaft 440 and third slotted cam shaft 460,allowing the first pin 445 and third pin 465 to remain in the same axialposition while the second pin 455 is moved rearwards 475 by pulling theouter grip 430 rearwards 475 towards the proximal end of the handle 400of the delivery system after the rotation of the outer grip iscompleted. By having axial slots of different lengths, the pins can bemoved axially by different distances when the outer grip is pulledrearwards 475 towards the proximal end of the handle. For example, thefirst axial slotted cam shaft 480 (associated with the outer shaft) isshorter than the second axial slotted cam shaft 485 (associated with thesheath), so that when the outer grip 430 is pulled rearwards 475, thesecond pin 455 is moved rearwards 475 along with the outer grip 430, thefirst pin 445 remains stationary until it connects with the end 490 ofthe first axial slotted cam shaft 480, after which it moves rearwards475 along with the outer grip 430, and the third pin 465 remainsstationary throughout the entire axial rearward 475 motion of the outergrip 430. In alternative embodiments, different lengths of axial camshafts can be associated with any of the pins, allowing for differentrearward travel distances, as desired. By moving the outer shaft back acertain distance after being pushed forward, while leaving the innershaft extended, the stent can be stretched out and fully deployedwithout the distal end of the stent being pulled back from the distalend of the cavity. In an alternative embodiment, there are no axial camshafts.

In one example embodiment, the outer grip 430 can be rotated throughapproximately 120° to fully move the sheath, inner shaft, and outershaft (and thus deploy the stent). In an alternative embodiment, alarger or smaller rotation of the outer grip 430, for example between90° and 360°, can be used.

Another example of a handle 400 for a delivery system with a rotationalcam mechanism 410 is shown in FIGS. 4C-4J. In this embodiment, thedelivery system includes a handle portion 400 and a hollow elongateshaft (not shown) extending from the distal end of the handle 400. Thehollow elongate shaft can include a distal end adapted to support anddeploy a stent within a cavity created within a vertebral body. Thehollow elongate shaft can include an inner shaft and an outer shaftadapted to engage a stent, releasably positioned at the distal end ofthe elongate shaft. A sheath can be positioned over the outer shaft andextend over the stent to maintain the stent in a collapsed configurationduring insertion through the cannula and into the cavity.

As with the embodiment of FIGS. 4A and 4B, the rotational cam mechanism410 includes three separate slotted cam shafts wrapped helically on asupport element 420 surrounding the central shaft 425 of the handle 400.An outer grip 430 covers the support element 420 and central shaft 425and engages with the support element 420. Pins 445, 455, 465 (associatedwith each of the outer shaft, the inner shaft, and the sheath) engagewith the slotted cam shafts 440, 450, 460 such that a rotation 435 ofthe support element 420 will force the pins 445, 455, 465 axially alongthe central shaft of the delivery device in a direct and distancecontrolled by the angle and direction of each slotted cam shaft 440,450, 460. In one embodiment, the pins 445, 455, 465 are positionedwithin a linear support sleeve 492 that is configured to ensure that thepins 445, 455, 465 can only move axially, either forwards 470 orbackwards 475, along the length of the handle 400. A schematicperspective view of the linear support sleeve 492 engaging one of thepins is shown in FIG. 4G, with FIG. 4H showing the support element 420positioned on the linear support sleeve 492.

A single axial slotted cam shaft 495 is located at the distal end of thefirst slotted cam shaft 440 and third slotted cam shaft 460, allowingthe first pin 445 and third pin 465 to moved rearwards 475 together. Aremovable cap 497 is placed on the proximal end of the handle 400 tocover a luer lock 498 adapted for engagement with a filler materialdelivery device, such a syringe.

A stent release button 482 is located on the handle 400 to actuatedisengagement of the stent from the elongate shaft once deployment andfilling of the stent is completed. The stent release button 482 can bedepressed and slid rearwards 475 towards the proximal end of the handle400 (i.e. away from the elongate shaft) to release the stent from theelongate shaft. In an alternative embodiment, two stent release buttonslocated opposite each other on either side of the handle 400 can beused. In a further alternative embodiment, any appropriate userinterface elements including, but not limited to, a dial, a switch, asliding element, or a button, can be used to activate the detachment ofthe stent from the elongate shaft, and/or to perform any other requiredfunctions.

FIG. 5 shows a handle 500 for a delivery system with a rotationalthreaded mechanism 510. The rotational cam mechanism 510 includes twoseparate threads wrapped helically on a support element 520 surroundingthe central shaft 525 of the handle 500. An outer grip 530 covers thesupport element 520 and central shaft 525 and engages with the threadson the support element 520. A first thread 540 is associated with thesheath of the delivery system, while a second thread 550 is associatedwith at least one of the inner shaft and outer shaft of the deliverysystem. A slotted control button 560 can provide a user control foradditional functions of the delivery system.

In operation, a rotation of the outer grip 530 will drive the sheath(associated with the first thread 540) in an axially rearward 575direction, while the inner and/or outer shaft (associated with thesecond thread 550) will be driven in an axially forward 570 direction.The helical angle of each thread will determine how far each element ismoved axially through the rotation of the outer grip 530. In analternative embodiment, larger or smaller helical angles can be used tomove one or more elements by any required distance, as appropriate. Inaddition, more threads, at any required helical angle, can beincorporated into the rotational threaded mechanism 510 to controladditional elements of the delivery system.

In an alternative embodiment, a geared mechanism can be used to controlthe movement of the inner shaft, the outer shaft, the sheath, and/or anyother appropriate element of the delivery system. The geared mechanismcan include a number of gear arrangements, including any appropriatelyconfigured and sized gears to move the shafts and/or sheath in differentdirections and by different distances, as required sequentially orsimultaneously. An example geared mechanism 610 can be seen in FIG. 6.

FIG. 6 shows a handle 600 for a delivery system with a geared mechanism610. The geared mechanism 610 includes a first gear arrangement 620,engaging the sheath, and a second gear arrangement 630 for controllingthe movement of one of more of the inner and outer shafts. In operation,a pin 640 can be moved in a rearward direction 675 by a user, thuspulling the sheath rearwards 475 by a distance corresponding to thelength of the slot 650. The first gear arrangement 620 will be driven bythe movement of the pin 640, which will in turn drive the second geararrangement 630 and push the inner shaft and/or outer shaft in a forwarddirection 670. Through careful selection of the slot 650 and gearingarrangements 620, 630, the sheath and the inner and/or outer shafts canbe moved by any appropriate distance and in either the forward 670 orrearward 675 direction. Different gearing arrangements to driveadditional and/or different elements can be used, as appropriate. In analternative embodiment, a dial associated with a gearing element, orother appropriate user control, can be used instead of, or in additionto, the pin.

FIG. 7 shows a handle 700 for a delivery system with a sliding beltmechanism 710. The sliding belt mechanism 710 includes a sliding outergrip 720 that is coupled to an inner sliding belt arrangement 730 thatforces an inner element 740 in a forward 770 direction as the slidingouter grip 720 is pushed in a rearward 775 direction by a user.

More specifically, the sheath is attached to the sliding outer grip 720,while the inner shaft and outer shaft are connected to the inner element740. By coupling the sheath, inner shaft, and/or outer shaft of theelongate shaft 750 to either the sliding outer grip 720 or the innerelement 740, each shaft and sheath can be moved forwards 770 orrearwards 775, as required. The sliding belt mechanism can providesimultaneous movement of the shafts and/or sheath, but may also providesequence in the movement of the shafts and/or sheath by delaying onefunction through the belt arrangement 730. As before, a luer lock 760can be placed at a proximal end of the handle 700 to provide a couplingelement for a cement deliver device, such as a syringe.

FIGS. 8A and 8B show a handle 800 for a delivery system with atriggering mechanism 810. The triggering mechanism 810 includes threeseparate slotted cam shafts positioned on a pair of cam plates 820within a trigger 825 that is pivotably connected to a support element830. Pins associated with each of the outer shaft, the inner shaft, andthe sheath of the elongate shaft 815 engage with the slotted cam shaftssuch that a closing of the trigger 825 will force the pins axially alongthe central shaft 835 of the delivery device in a direct and distancecontrolled by the angle and direction of each slotted cam shaft. Thisconfiguration can result in a simple mechanical delivery system that iseasy to use.

More specifically, a first slotted cam shaft 840 engages with a firstpin 845 attached to the outer shaft of a delivery system. A secondslotted cam shaft 850 engages with a second pin 855 attached to theinner shaft of the delivery system. And, a third slotted cam shaft 860engages with a third pin 865 attached to a sheath. As a result, as thetrigger 825 is closed by being pivoted 885 into the support element 830about a pivot point 880, the first pin 845 and second pin 855 will beforced axially forward 870 toward the distal end of the handle 800,resulting in the inner shaft and outer shaft being extended outwardsfrom the distal end of the handle 800 (and therefore compensating forany foreshortening of the stent during deployment). Simultaneously, thethird pin 865 will be pulled axially rearwards 875 toward the proximalend of the handle 800, resulting in the sheath being pulled rearwards875 towards the handle 800 (and therefore exposing the stent).

The first slotted cam shaft 840 includes a bend 890, resulting in thefirst pin 845 (and therefore the outer shaft) being moved forward 870initially before being moved in a rearward direction 875 during a secondportion of the closing motion. In alternative embodiments, any one ormore of the cam shafts can be curved, bent, and/or angled in anyappropriate manner to produce the required forwards and/or rearwardmovement of each element of the delivery system. In a furtheralternative embodiment, none of the cam shafts include a bend.

As before, a luer lock 895 can be placed at a proximal end of the handle800 to provide a coupling element for a cement delivery device, such asa syringe. In one embodiment, a bump 892 on a rear portion of one orboth of the cam plates 820 can engage and force the release of an endcap on the handle 800, thus exposing the luer lock 895 and prompting theuser to begin the next stem of the process. In an alternativeembodiment, no bump is required, and the end cap of the handle 800 isinstead removed manually.

In one embodiment, the delivery system may include a locking mechanismadapted to releasably lock the delivery system within a cannula in arequired circumferential orientation, to ensure the correct positioningof the stent within the cavity created within the vertebral body. In oneembodiment, a spring loaded locking mechanism on the cannula may engagea portion of the handle of the delivery system to releasably lock it inplace, with one or more buttons, switches, knobs, or other appropriateuser elements, either on the cannula or on the handle of the deliverysystem, releasing the locking mechanism when the delivery system is tobe removed. In one embodiment, the cannula can include a sliding elementadapted to engage a protruding flange at a distal end of a handle of adelivery system to releasably lock the delivery device into the cannula.An example cannula 900 including a sliding element 910 for releasablyengaging a protruding flange of a delivery system 920 can be seen inFIG. 9. In further embodiments, any other appropriate means ofreleasably locking the delivery system to the cannula in a requiredcircumferential configuration can be used.

In one embodiment, a key may be positioned on the hollow elongate shaftto mate with a slot in the cannula to ensure that the delivery system isinserted into the cannula in the desired orientation. In an alternativeembodiment, at least a portion of the distal end of the handle of thedelivery system can be configured to mate with a portion of the cannula,thus ensuring the positioning of the delivery system in the correctorientation.

In one embodiment, as described above, the delivery system can be usedto deploy a stent within a cavity created within a vertebral body,wherein the handle is adapted to control multiple components of thedelivery system with a movement of a single user control mechanism, suchas a rotation, sliding, or triggering of a user control mechanism.

Another example delivery system 1000, including a rotating user controlmechanism 1040 on the handle 1010, can be seen in FIGS. 10A to 10C. Therotating user control mechanism can include, but is not limited to, arotational cam mechanism or a rotational threaded mechanism. In analternative embodiment, a gear mechanism, a sliding belt or triggeringmechanism, or any other appropriate mechanism, as described herein, canbe used in place of the rotating user control mechanism 1040 to move theinner shaft, outer shaft, and/or sheath, as required.

As with certain other embodiments of the invention described herein, thedelivery system 1000 includes a handle 1010, an elongate shaft 1020,including a key component 1025, a top cap 1030, and a number of userinterface elements. The user interface elements include a rotating usercontrol mechanism 1040 and two stent release buttons 1050. In analternative embodiment, a lesser or greater number of stent releasebuttons can be used. In one embodiment, the stent release buttons 1050can be replaced by one or more switches, knobs, sliding elements and/orother appropriate user elements, or combinations thereof, as required.

In one embodiment, one or more additional user input mechanisms 1060 canbe incorporated into the handle 1010. These user input mechanisms 1060can include, but are not limited to, delivery system release mechanisms,stent deployment and/or release mechanisms, a mechanism for controllingthe curvature of a distal end of one or more of the elongate shafts, orany other appropriate control, delivery, and/or deployment functioncontrol elements. In alternative embodiments, the user input mechanisms1060 can include, but are not limited to, buttons, switches, dials,sliding elements, or other appropriate mechanical or electrical inputelements. In one example embodiment, the user input mechanism 1060 is adelivery system release mechanism adapted to allow the delivery system1000 to be unlocked and disengaged from a cannula or other workingchannel. Again, any other appropriate user element on the deliverysystem 1000 and/or cannula can be used to release the delivery system1000 from the cannula upon completion of the stent deployment. In afurther alternative embodiment, there are no additional user inputmechanisms 1060.

A method of using the delivery system 1000, in accordance with oneembodiment of the invention, can be seen in FIGS. 11A to 11D. Thisembodiment includes first inserting the delivery system 1000 into thecannula and locking it in position in a predetermined set orientation.FIG. 11A shows the delivery system 1000 in its initial configurationafter insertion into a cannula (not shown). The rotating user controlmechanism 1040 on the handle 1010 of the delivery system 1000 can thenbe rotated, resulting in the outer sheath of the elongate shaft beingretracted while the inner and outer shafts are moved forward tocompensate for any foreshortening of the stent during retraction of thesheath, as described above. FIG. 11B shows the delivery system 1000after rotation of the rotating user control mechanism 1000.

Once the sheath has been retracted, the top cap 1030 of the handle 1010can be removed, and a syringe or other cement deployment device can beattached to a luer lock 1070 (or other appropriate connection means) atthe proximal end of the handle 1010. FIG. 11C shows the handle 1010 witha top cap 1030 removed. Cement can then be injected through the deliverysystem 1000 and into the stent. Once the required amount of cement hasbeen delivered into the stent, the syringe can be removed.

The stent release buttons 1050 can then be depressed and slid towardsthe proximal end of the handle 1010 (i.e. away from the elongate shaft1020) to release the stent from the elongate shaft 1020. FIG. 11D showsthe delivery system 1000 with the stent release buttons 1050 depressedand slid towards the proximal end of the handle 1010 to release thestent. The delivery system 1000 can then be safely removed by activatinga delivery system release button, or other appropriate mechanism, todisengage the delivery system 1000 from the locking mechanism on thecannula, and removing the delivery system 1000 from the cannula whileleaving the disengaged stent within the vertebral body.

In one embodiment of the invention, a distal end of an elongate shaftcan include a preformed curvature. The elongate shaft can include, butis not limited to, an inner shaft, an outer shaft, a tubular sheath, aflexible guidewire, and an internal polymer extrusion. The elongateshaft, or a portion thereof, can be constructed from a metal including,but not limited to, nitinol, steel, aluminum, or any other appropriatematerial such as, but not limited to, a plastic. The distal end of theelongate shaft can also include a slotted arrangement allowing thedistal end of the elongate shaft to curve and/or preferentially bucklein a specified direction. This curving of the distal end of the elongateshaft can be controlled by a curvature control mechanism located, forexample, within the handle of the delivery system. In an alternativeembodiment, the elongate shaft can preferentially buckle in response toa force imposed on the distal end of the elongate shaft by thesurrounding bone and/or tissue within the vertebral body. Exampleelongate shafts with preformed and controlled curvature and/orpreferential buckling are described in the related U.S. patentapplication Docket No. SOT-004, entitled “Devices and Methods forVertebrostenting,” and filed of even date herewith, and U.S. applicationSer. No. 11/091,232, the disclosures of which are being incorporatedherein by reference in their entirety.

In one embodiment of the invention, a stent for use with the apparatusand methods described herein can include an attachment mechanism at adistal end thereof (i.e. at the end of the stent remote from theelongate shaft). This attachment mechanism can releasably attach to oneor more elongate elements extending through the interior of the elongateshaft.

In operation of one embodiment, the elongate element extending throughthe elongate shaft and attaching to the distal end of the stent can beused to hold the stent in a collapsed configuration prior to deploymentin place of, or in addition to, a sheath. When the stent is ready to bedeployed, the attached elongate element can be used to pull the distalend of the stent rearwards towards its proximate end (i.e. the end ofthe stent releasably attached to the distal end of the elongate shaft)in order to assist in expanding or to forcibly expand the stent. Thismay be advantageous in embodiments of the invention using a stifferand/or thicker stent, that may benefit from additional external forcesto assist in its expansion or to provide positive forces on the walls ofa cavity in which it is inserted. For example, a stiffer stent, with amore substantive mesh structure, can be used to provide a jacking forceto expand the size of a cavity and/or jack or push two walls of acollapsed vertebral body apart. In this embodiment, the self-expandingnature of the stent may not provide sufficient force in and of itself toprovide a jacking force of desired magnitude. The additional forceneeded to allow the stent to jack the walls apart can be provided by thepulling force applied to the distal end of the stent by the releasablyattached elongate element. After the stent has been expanded, theelongate element can be released from the stent and removed through theelongate shaft.

The elongate element releasably attached to the distal end of the stentcan also be advantageous in embodiments where a cavity has not beenreamed out in the vertebral body, or other structure, but rather only adrill hole has been created in the vertebral body sufficient in size toreceive the stent in a collapsed configuration. In this embodiment, theelongate element can be used to pull on the distal end of the stent andassist in expanding it into the body structure surrounding the drillhole. This method may be useful, for example, in the treatment ofseriously degraded vertebral bodies, where the stent can be expandedinto the surrounding degraded bony structure with nominal additionalforce.

An example stent deployment method including a stent with an attachmentmechanism at its distal end can be seen in FIGS. 12A to 12D. In thisembodiment, a stent 1205 is releasably attached at its proximal end 1210to an elongate shaft 1215 including an inner shaft 1220 and an outershaft 1225. The means of releasably attaching the stent 1205 to theelongate shaft can include any of the mechanisms and methods describedherein.

A ferrule 1230 is placed against the interior wall of the distal end1235 of the stent 1205, with a locking ring 1240 holding the ferrule1230 in place against the wall of the distal end 1235 of the stent 1205,for example by a radial interference fit. The ferrule includes a hollowproximate end 1245 with two slots 1250 formed in the walls thereof. Theslots 1250 are adapted to releasably engage an elongate attachmentelement 1255 with a pair of tangs 1260 at a distal end thereof. Thetangs 1260 are bent in towards the central axis 1275 of the elongateattachment element 1255 such that the tips 1265 of the tangs 1260 can beextended into the hollow proximate end 1245 of the ferrule 1230. In analternative embodiment, a greater or lesser number of slots 1250 andcorresponding tangs 1260 can be used.

Once the tips 1265 of the tangs 1260 have been extended into the hollowproximate end 1245 of the ferrule 1230, an inner rod 1270 is extendedthrough the elongate attachment element 1255 to abut against the innerwalls of the tangs 1260. By pushing the inner rod 1270 forward towardsthe distal end 1235 of the stent 1205, the inner rod 1270 pushes theends of the tangs 1260 outwards from the central axis 1275 of theelongate attachment element 1255 such that the tips 1265 are forced intothe slots 1250 in the ferrule 1230. As a result, the elongate attachmentelement 1255 becomes releasably coupled to the ferrule 1230 and cantherefore provide a pulling force to the distal end 1235 of the stent1205.

In operation, the elongate attachment element 1255 is coupled to theferrule 1230 prior to deploying the stent 1205 in the vertebral body. Tofacilitate insertion of the stent 1205 through the cannula, and into thevertebral body, the elongate attachment element 1255 is pushed forwardsagainst the distal end 1235 of the stent 1205 to force the stent 1205into a collapsed configuration, as shown in FIG. 12A. In one embodimenta sheath can be extended over the stent 1205 to hold the stent 1205 in acollapsed configuration, with the sheath being retracted once the stent1205 is in position within the vertebral body, as described above. In analternative embodiment, no sheath is required, with the elongateattachment element 1255 providing sufficient force to maintain the stent1205 in a collapsed configuration.

Once the stent 1205 has been positioned correctly within the vertebralbody, the elongate attachment element 1255 can be pulled back by a setamount, dependent upon the size and shape of the stent 1205, thuspulling on the distal end 1235 of the stent 1205 and forcing it toexpand to its deployed configuration, as shown in FIG. 12B.Advantageously, as the distal end 1235 of the stent 1205 is pulled back,the proximal end 1210 of the stent can be advanced or pushed forward, inorder to expand the stent 1205 while leaving a midpoint of the stent1205 in essentially a fixed position in the cavity in the vertebralbody. This coordinated action of retracting the distal end 1235 whileadvancing the proximal end 1210 can be accomplished using the types ofmechanisms described above located in the handle.

After the stent 1205 has been positioned in its deployed configuration,the inner rod 1270 can be pulled out from the elongate attachmentelement 1255, as shown in FIG. 12C. As the inner rod 1270 is pulled out,the tangs 1260 collapse back into their initial configuration (i.e. bentin towards the central axis 1275 of the elongate attachment element1255). This in turn removes the tips 1265 of the tangs 1260 from theslots 1250 of the ferrule 1230, thus disengaging the elongate attachmentelement 1255 from the ferrule 1230. The elongate attachment element 1255can then be pulled out from the ferrule, leaving the distal end 1235 ofthe stent 1205 free.

In one embodiment, the elongate attachment element 1255 is a hollowneedle adapted to inject cement into the stent 1205. In operation, oncethe inner rod 1270 has been removed and the elongate attachment element1255 detached from the ferrule 1230, cement can be injected through theelongate attachment element 1255 and into the interior of the stent 1205to fill the stent 1205, as shown in FIG. 12D. After the stent 1205 hasbeen filled with cement to the volume required, the elongate attachmentelement 1255 can be removed and the stent 1205 detached from theelongate shaft. In an alternative embodiment, the elongate attachmentelement 1255 can simply be removed from the elongate shaft 1215 afterdeployment of the stent 1205, with cement, or any other appropriatefiller material, being injected thereafter into the stent 1205 directlythrough the inner shaft 1220 of the elongate shaft 1215, or through aseparate cement injection element.

The elongate attachment element 1255, elongate shaft 1215, ferrule 1230,locking ring 1240, and inner rod 1270 can be constructed from materialsincluding, but not limited to, a metal (e.g. nitinol, steel, aluminum,or any other appropriate metal), a plastic, and/or a composite material.

In an alternative embodiment, the ferrule 1230 can be attached to thedistal end 1235 of the stent 1205 by any other appropriate method, suchas, but not limited to, being glued to, welded to, or otherwise attachedto the stent 1205. In further alternative embodiments, the elongateattachment element 1255 can be releasably attached to the ferrule by anyappropriate mechanical, electrical, thermal, or magnetic connectionmeans.

In alternative embodiments of the invention, any appropriate material,or combination of materials, may be used for the components of thedelivery system. Appropriate materials include, but are not limited to,stainless steel, aluminum, plastics, textiles (for the sheath),composite materials, or any combination thereof. The delivery system maybe configured with all, or only some of, the components describedherein, depending upon the specific requirements of the system.

The delivery system may be configured to deliver cement, cementanalogue, or other appropriate filler material, to any appropriatestent, bag, or other fillable device. In one embodiment, the stent neednot have holes for the directed exit of the cement into the vertebralbody. The delivery system may be configured to delivery a stent, orother device, to a cavity in any bony structure, and not just avertebral body. Additionally, any appropriately shaped cavity may betreated with the above-mentioned delivery system and stents.

It should be understood that alternative embodiments, and/or materialsused in the construction of embodiments, or alternative embodiments, areapplicable to all other embodiments described herein.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The foregoingembodiments, therefore, are to be considered in all respectsillustrative rather than limiting the invention described herein. Scopeof the invention is thus indicated by the appended claims, rather thanby the foregoing description, and all changes that come within themeaning and range of equivalency of the claims are intended to beembraced therein.

1. A method of deploying a stent within an enlarged curvilinear voidcreated in a bony structure, the method comprising the steps of:inserting a distal end of a stent delivery system through a cannula andinto a curvilinear void created in a bony structure; deploying aself-expanding cement-directing stent within the curvilinear void,wherein the self-expanding stent is releasably attached to the distalend of the stent delivery system; attaching a cement injecting syringeto a proximal end of the stent delivery system; injecting cement throughthe stent delivery system and into the stent; terminating the cementinjection when the volume of cement injected exceeds an interior volumeof the expanded stent; and releasing the stent from the stent deliverysystem.
 2. The method of claim 1, wherein the self-expandingcement-directing stent comprises a multifilament braided, polymerimpregnated, self-expanding, cement-directing stent.
 3. The method ofclaim 1, wherein the stent delivery system comprises a handle and anelongate shaft, and wherein the stent is releasably attached to a distalend of the elongate shaft.
 4. The method of claim 3, wherein the stentis released by actuating a user control mechanism on the handle.
 5. Themethod of claim 3, wherein the elongate shaft comprises at least one ofan inner shaft, an outer shaft, a tubular sheath, a flexible guidewire,and an internal polymer extrusion.
 6. The method of claim 5, whereinprior to the deploying step the self-expanding cement-directing stent iscollapsed on a distal end of at least one of the inner shaft, theguidewire, and the polymer extrusion.
 7. The method of claim 6, whereinthe self-expanding cement-directing stent is deployed by retracting atleast one of the inner shaft, the outer shaft, the flexible guidewire,and the polymer extrusion.
 8. The method of claim 5, wherein prior tothe deploying step the self-expanding cement-directing stent isrestrained in a collapsed condition by the tubular sheath.
 9. The methodof claim 8, wherein the self-expanding cement-directing stent isdeployed by slideably retracting the tubular sheath to allow the stentto self-expand within the enlarged curvilinear void.
 10. The method ofclaim 1, wherein the deploying step comprises actuating a rotating cammechanism.
 11. The method of claim 3, wherein the stent is furtherreleasably attached at a distal end thereof.
 12. A stent delivery systemfor deploying a stent within an enlarged curvilinear void created in abony structure comprising: a handle; an elongate shaft adapted toreleasably hold a self-expanding cement-directing stent at a distal endthereof, wherein the elongate shaft comprises a sheath and at least oneof an inner and an outer shaft; and at least one user control mechanismadapted to deploy the stent.
 13. The system of claim 12, wherein the atleast one user control mechanism comprises a rotating cam mechanism. 14.The system of claim 13, wherein actuating the rotating cam mechanismretracts the sheath towards the handle.
 15. The system of claim 14,wherein actuating the rotating cam mechanism simultaneously extends thedistal end of at least one of the inner and the outer shaft away fromthe handle.
 16. The system of claim 12, wherein a distal end of thehandle comprises an interface element adapted to releasably engage atleast a portion of proximal end of a cannula.
 17. The system of claim12, further comprising a stent release mechanism adapted to release thestent from the elongate shaft.
 18. A user control mechanism for a stentdelivery device, comprising: a support element; at least one cam shafthelically positioned on the support element; a linear support sleeve;and at least one pin engaging the cam shaft and the linear supportsleeve, wherein the cam shaft and the linear support sleeve are adaptedto force the pin linearly along an axial extent of the user controlmechanism upon a rotation of the support element.
 19. The user controlmechanism of claim 18, wherein the at least one pin is attached to anelongate shaft extending from a distal end of the user control element.20. The user control mechanism of claim 19, wherein the elongate shaftcomprises at least one of an inner shaft, an outer shaft, and a sheath.